DESCRIPTION (Verbatim from the Applicant's Abstract): The long-term objective of this research is to understand the natural history of early osteoarthritis (OA), and cartilage aging to improve diagnosis, treatment, and management of patients with rheumatic disease. The goal of this project is to develop and validate a reproducible, quantitative, imaging technique that is sensitive to structural changes in the extracellular matrix that precede the loss of articular cartilage. This proposal is based on the hypothesis that the increase in cartilage water content, and permeability, and loss of tissue anisotropy, known to occur with early degeneration; will increase the Magnetic Resonance Imaging (MRt T2 of cartilage. Therefore, a quantitative measurement of cartilage T2 will provide a sensitive noninvasive marker of early cartilage damage. This study will address the following specific aims: Specific Aim 1: Develop and validate methods for obtaining and analyzing quantitative MRI T2 maps of human knees. Specific Aim 2: Test the hypothesis that compression of articular cartilage results in a measurable decrease in T2 values of superficial cartilage. Specific Aim 3: Validate the technique in patient with potential cartilage damage by determining inter- and intra reader reliability and correlating results of cartilage T2-mapping with the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index, and quantitative arthroscopic evaluation. Measurement of cartilage T2 provides a unique opportunity to observe early m about structural changes of the extracellular matrix, and monitor these changes over time. In this proposal we will develop, validate, and refine the methodology needed to obtain reproducible quantitative T2 maps of human knees. At the conclusion of this project we will have 1) developed and tested methods for data acquisition, analysis, and interpretation, 2) Evaluated the effect of body habitus and activity on cartilage T2, and 3) Validated T2 mapping with OA symptoms, and arthroscopy.